DE2161178A1 - Process for the polymerization of vinyl aromatic compounds - Google Patents

Description

DR. MOLLER-BORe D] P1_-PHYS. DH. MANITZ OiPu.-CHEM. DK. DEUFEL DIPL.-ING. FINSTERWALD D1PL.-ING. GRÄMKOW

PATENT LAWYERS

8.BK.

3h - J 1078

'j? HE ΙΙΗΕΕίΙίΑΐΙΟΙίΔΙ SBTDHETIC RUBBER COMEAITX LIMITED Brunswick House, Brunswick Place, Southampton, England

Process for the polymerization of vinyl aromatic

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Priority: Great Britain of December 10, 1970 No. 53757/70

The invention relates to a process for anionic polymerization of at least one of the vinyl aromatic monomers styrene and / or hydrocarbon-substituted styrenes with polymerization of the monomer (s) in the presence of a metal of the first main group of the periodic table or a Hydrides or a hydrocarbon compound thereof.

Ec are already methods for the polymerization of vinyl aromatic Connections, d. H. a single vinyl residue directly on compounds containing an aromatic nucleus, wherein cd.e connection ": ·: ·! nit a. B. halogen or hydrocarbon .L-entoij. to be substituted komien, known. These methods include H-isf.g, bead or emulsion polymerizations Vei-woridunr: free radical catalysts and isothermal Pol7 / i..erisatiorien in hydrocarbon solution using

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an anionic catalyst system such as Lithium alkyl. In the production of vinyl ar omätijcheii For polymers according to such methods, the monomer is generally required in practically pure form. The vinyl aromatic Monomers is usually made by the dehydrogenation of its alkyl aromatic precursor compound, for example, styrene is obtained by the dehydrogenation of ethylbenzene. A subsequent separation of the vinyl aromatic Monomers from the other dehydrogenation products and also from unconverted oil-runner compound in the product resulting from the reaction was generally required.

In the known working methods, temperature control plays an important role in the production of a satisfactory end product. For example, the Temperattir in use was kept an anionic system in a solution in spite of the decreased reaction rates low, typically from 30 ⁰ C to JO ⁰ G to the undesirable decrease in molecular weight of the polymer product and to any other occurring when high temperature complications, z. B. low conversion yield to avoid. The adverse effects of the Ten peratursteigerung in such anionic polymerizations were of E. U. Duck, MH ^-. Thornber and LVJ Saunders in Rubber and Plastics Age, £ 4 (1964), pages 274 and 2-6.

JTerner is in UK Patent 842,665 Gin. The method described for the preparation of polystyrene, which comprises preparing a styrene solution in an inert hydrocarbon having a boiling point close to that of styrene, the polymerization of the styrene in this solution at a 'i'enperatur in the range of about 40 to 100 ⁰ C in the presence of a catalyst of dispersed sodium with a small partial

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size, the temperature in the polymerization stage being controlled by boiling the solution at a controlled pressure, removing the sodium from the polynorizate solution, and finally removing the solvent from this solution. One feature of this procedure concerns the step of making the styrene solution by dehydrogenation of ethylbenzene, which is contained in a C _Q aromatics stream obtained from hydroforming Har> htha

is, the resulting solution of the styrene monomer of tar and water is practically freed.

It has now been found that it is possible to obtain useful products of high linear weight if, contrary to the prior art practice in the anionic polymerization of vinyl ar or compounds, the temperature of the reaction mixture increases in an uncontrolled manner Values are allowed to rise well above those previously considered applicable.

In particular, the faster production of vinyl aromatic High molecular weight polymers can be carried out by anionic polymerization of the monomers not separated from the discharge stream of a dehydrogenation reaction.

The successful process for anionic polymerization of at least one of the vinyl aromatic monomers »styrene UT-d / or Ircliienwasserstofisubstituicrte styrenes under PoIyr.erisc.tior- ^ ec / ucr honoring in the presence of a metal of the first major series of the periodic table or of a hydride or a hydrocarbon compound thereof üich from the fact that as starting materials for the polymerization the astonished from a dehydrogenation reaction,: .iiidester.s 5 Geu.% of the monomer (s) containing hydrocarbons used v / ground, and that at least part of the polymer! cn swarm e in the reaction mixture with disruption

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BATH

^{the temperature is retained above 100 0} O for at least part of the reaction time. . '

It is preferable to use 50% or more of the heat of polymerization retained in the reaction mixture.

In a further preferred embodiment of the invention, the anionic polymerization process is carried out as described above, but at least 80 % of the heat of reaction is retained in the reaction mixture. The reaction can be carried out under practically adiabatic conditions. A polymer with an intrinsic viscosity, measured under the conditions listed below, of at least 0.5 is preferably obtained.

The term intrinsic viscosity as used in the specification refers to the intrinsic viscosity of approximately 0.1 w / v. % solution in toluene of laboratory purity, determined in an Ostwald viscometer at 25 ⁰ C.

In a further advantageous embodiment of the invention, preferably to the continuous process for the anionic polymerization, the temperature of the reaction mixture, the polymerization reaction is above 100 ⁰ C held for at least half the duration and Umxirandlung of monomers! carried out to polymers to at least 80 % , a polymer with an intrinsic viscosity of at least 0.65 being obtained.

The temperature rise Δ t of the reaction mixture at the Reaction mainly depends on the heat of polymerization and the concentration of vinyl aromatic compound, the other hydrocarbons in the mixture having less influence.

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The vinyl aromatic compound can practically in the form of the products given off from a dehydrogenation reaction are polymerized. In the case of styrene as monomers styrene, for example, as a solution in ethylbenzene (which generally also contains a small percentage of loluene, benzene and other homologues), which, directly by dehydrating ethylbenzene or an ethyl * benzene / xylene mixture - as is the case with the hydroforming of Naphtha is generated - was obtained, polymerized. on in this way there is no separation of the monomer from the hydrocarbon stream originating from the dehydrogenation reaction required prior to using the discharged stream as starting materials for the polymerization.

Similarly, «f-methylstyrene can be used prior to separation obtained as a mixture with isopropylbenzene and in this form ' are polymerized by the process of the invention. The concentration of the vinyl aromatic monomer (s) in the Dehydration release stream may be 5 wt% to e.g. B. 90 wt.% Or be more, with concentrations of 30 wt.% To 60 % By weight are usually obtained. It is essential that the starting materials be practically free before polymerization of air, oxygen and moisture as well as other contaminants that are associated with the polymerization catalyst react or otherwise interfere with the polymerization reaction. If necessary, a separate cleaning stage can be used may be required to remove such contaminants. If in the description on monomers practically in the form of the output stream of a dehydrogenation reaction is referred to, this also relates to the output streams of such a Were subjected to the purification stage. It can be in excess of the amount required for the polymerization Catalyst can be used to react with the impurities, but this is costly and uneconomical.

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'The polymerization is carried out by means of an anionic catalyst initiated, which is a metal of the main group of the periodic table or a hydride or a hydrocarbon compound includes such a metal. Examples of suitable metals are lithium, sodium and potassium. I & thium and Hydrides or hydrocarbon compounds with z. B. 1 to 6 carbon atoms thereof are preferred. Examples of suitable hydrocarbon radicals are alkyl, including cycloalkyl, aryl and aralkyl radicals. Advantageous metal hydrocarbon catalysts are methyl lithium, ethyl lithium, butyl lithium, amyl lithium, sodium naphthalene, benzyl lithium and phenyllithium. Idthium alkyls, especially lithium butyl are preferred. The amount of catalyst required is generally 5 to 15 mmol / l of vinyl aromatic! Monomers, however, they can also be as low as about 2.5 mmol / l lie. The catalyst can be in the form of a solution in a suitable solvent, e.g. B. hexane, can be used.

In the case of lithium butyl polymerization of styrene, the concentration of idthium butyl is usually in the range of 0.035 Ms 0.11 TIe. per 100 ¹ SIe. Sbyrene, the minimum applicable value being about 0.020 TIe. amounts to. These amounts relate to the active catalyst, ie the catalyst actually used to initiate the polymerization. If impurities are present in the monomer feed, some catalyst will be consumed in scavenging reactions and therefore will not be available to initiate the polymerization.

In general, the intrinsic viscosity of the final polymer varies inversely proportional to the catalyst concentration. In this way, by varying the catalyst concentration and the initiation temperature, polymers with a large number of internal viscosities can be obtained. The intrinsic viscosity of the product is advantageously

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at least 0.5 "and preferably 0.65 Ms 1.4.

The initiation temperature of the mixture is chosen so that an uninterrupted rate of polymerization is obtained when the mixture is brought into contact with the catalyst and, in general, temperatures above 120.degree. C. are not required. Typically, initiation temperature s in the range of 30 ° 0 to 100 ⁰ G, z. B. 40 ^{0 0} to 90 ⁰ C and preferably 40 ⁰ C to 70 ° G applied; Initiation temperatures below about 15 ⁰ G result in a very slow reaction. In general, a substantial reduction in the intrinsic viscosity of the end polymer is obtained when the initiation temperature is increased, and in this way some control of the intrinsic viscosity of the end polymer can be achieved.

Once the polymerization starts, the temperature of the reaction mixture rises because a portion, preferably 50 % or more, of the heat of polymerization is retained in the reaction mixture. Advantageously, at least 80 % and very particularly preferably practically all of the heat of polymerization is retained in the mixture. The heat of polymerization of a vinyl aromatic monomer can be determined experimentally, and in the case of styrene values ranging from 16.1 to 17.7 kcal / mol have been reported depending on the method of determination used. A generally accepted value is 16.7 kcal / mole and the reference to percentages of polymerization currents in the description can be converted to absolute values using this number for the conversion factor. In this way, the amount of heat retained in the reaction mixture can be determined from the knowledge of the temperature rise in any given reaction and the specific heats of the constituents of the reaction mixture and thus the proportion of the theoretically generated heat.

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amount can be calculated in a simple way.

The temperature rise is such that the temperature of the reaction mixture is above 100 ° C. for at least part of the reaction time and preferably at least half of the reaction time. Towards the end of the reaction, for example, 200 ⁰ or more can be reached. The reaction conditions are preferably such that the polymerization can be completed quickly. The reaction time is preferably less than 1 hour, particularly preferably 50 minutes or less. Δ t for the reaction mixture is preferably at least 100 ^° C.

The product at the end of the reaction is at a temperature of 100.degree. C. or more, preferably 180.degree. C. or more. Easily removed in the preferred final temperatures of 180 ⁰ C or more Uird the polymer product of volatile components without the addition of large amounts of heat is required, as it is manufactured in procedures in which the ELymerisat by conventional, the application of much lower polymerization temperatures comprehensive processes, required are. Another advantage is that the product is melted and is therefore in an ideal form for further processing, e.g. pelletizing or casting or compression molding.

As described above, the intrinsic viscosity can be obtained Polymerizates somewhat by changing the initiator structure and the amount of active catalyst varies. In general, results can be satisfactory using a suitable combination of these parameters within the area ABC of that shown in FIG. 1 of the drawing Diagram can be achieved. Products with a commercially advantageous intrinsic viscosity have been particularly

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specially obtained in a suitable manner by choosing the parameters within the area DEB ¹ GH of the diagram.

The monomers used in the polymerization process of the invention are styrene and hydrocarbon substituted styrenes, e.g. B. on the benzene nucleus or in the vinyl side chain by a hydrocarbon radical, e.g. B. a * hydrocarbon radical with 1 to 4 carbon atoms, substituted styrene. Examples of suitable, hydrocarbon-substituted styrenes are itf-methylstyrene, vinyltoluene and homologues of these compounds. Styrene is industrially produced in great hate by the dehydrogenation of ethylbenzene, as already described above, and the process according to the invention enables the production of an industrially valuable styrene polymer without the need for an expensive separation of the styrene from the ethylbenzene.

The polymerization reaction is suitably carried out as a continuous one Process carried out, for example, in a tubular reactor, which can be an insulated tube. It can ■ however, an approach-based procedure is also used, and any pressure vessel in which the heat of polymerization can be easily retained can be used v / earth. Pressure is preferably applied to the roaming system so that all reactants are in the liquid Phase remain, e.g. B. a pressure of at least 3.5 abü (50 p.s.i.g.), preferably 7> 0 to 14.1 abü (100 to 200 p.s.i.ß.). If necessary, part of the steam, in particular of hydrocarbons other than monomers, removed from the reaction system. A continuous one Method is preferred, and any suitable form of device for carrying out such a method Inb shown in FIG. A source (i) of vinyl aromatic compounds unr; on, e.g. B. Sbyrol, namely the Abgäbest; rom. ouLor Do-

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hydrogenation reaction involving the vinyl aromatic compound generated from a forerunner connection hereof is with connected to a dryer (2) which leads to a preheater (3). The raw materials are in the preheater heated to the desired initiation temperature before being transferred to the bottom part of an upright tubular reactor (4) step through, although it should be noted that this stage is not always required.

Next is a catalyst, e.g. B. in solution, which is under a Upholstery of z. B. nitrogen held in a container (5) is also led to the lower part of the reaction vessel. The entire anionic polymerization proceeds uninterruptedly forty the monomer (s) rise in the reactor, for example at a speed of 0.3 m / min, the temperature of the reaction mixture being given is monitored at suitable points. The reaction mixture is fed from the top of the reactor to a heated volatilizer (6) in which any nonreactive Hydrocarbons and any unreacted / unreacted monomers under vacuum for the recirculation can be removed through an outlet (7). The melted polymer product that is caught is sent through a pump injection device (8) in which it is deformed into a plurality of strands (9). These strands are oinered by a water cooling bath (10) Pelletisiervorrichbung (11) out in which they are too small Pieces or granules are cut. These were sifted out in a sieve (12) and finally to a storage crusher (13) transferred.

Fillers, reinforcing agents and / or slip aids can become clogged. For example, 3in can be more unsaturated Rubber such as polybutadiene and / or natural rubber or similar polymers, advantageously in solution in one suitable solvent of the monomers will.

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The invention is explained below using an example.

example

Using the apparatus described above, a 4-0 wt.% Solution of styrene in ethylbenzene, formed by the coming from the dehydrogenation reaction of ethylbenzene output stream, and preheated over alumina dried to approximately 60 ⁰ C before a clad, vertical 6.7 m tubular reactor 10.2 cm in diameter was passed. At the point at which the solution entered the reaction vessel, a 15 Gevr./W.% Solution of Idthiuinbutyl in hexane in a Henge of 0.066 TIe. Lithium butyl per 100 teas. Styrene injected (on a weight basis). Separate tests showed that approximately 0.04-3 TIe. per 100 tie. Styrene were present as the active catalyst. The mixture was maintained under a pressure of 10.5 atmospheres (150 psig). As the mixture rises in the reactor, polymerization took place, the strong exothermic reaction causing the mixture temperature to rise. The residence time was about 30 min and the Eidtemperatur approximately 190 ⁰ C. The conversion of styrene into polystyrene was et v / a 96%. The mixture \ rurde transferred to a Verflüchtigungseinrichtung in which the residual styrene and ethylbenzene were removed under high vacuum and at 24-0 ⁰ O. The molten polystyrene was removed by a pump and pressed through a press head and recovered.

The intrinsic viscosity of the product was 0.89. Other physical properties were also determined by them are listed in the table below.

Using the heat of polymerization of styrene to 16.7 kcal / Hol and the (at all temperatures as constant

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assumed) specific heat of the mixture to 0.5, the theoretical temperature rise to 123 ⁰ C can be calculated. The observed temperature rise was 150 °, therefore it can be seen that practically all of the heat of polymerization was retained in the reaction mixture, ie that the reaction was carried out under practically adiabatic conditions.

Tabel

Investigative
method Investigative
conditions Result Tensile strength
speed ASTM
D.638-67T Type 1
CH.S. 0.5 ClVmin 592 kg / cm ² strain ASi'.H.
D.658-67T - Flexural strength
speed ASTM
D.790-66 1/8 ": γ1 / 2" χ5 "
Rod
CH.S. 0.5 CM / min 1100 kg / cm ² Notched impact
strength ASTM
D. 256-56 (1961) 1/8 "x1 / 2" x2 1/2 "
Stick _oc - o, -,
25 k 2.29 kg / cm ² Bending module ASTM
D.790-66 1/8 "xi / 2" rod 4.44 30 ⁴
kg / cm ^ Rockwell
hardness ASTM
D.785-65 R&M scale
1/8 "disc
at 25 ⁰ C R 115 M 70 Heat defor
mung temperature
rature ASTM
D.648-56
(1961) 4.64 kg / cm ²
(66 psi) 94.5 ° C ■ Melt flow
index ASTM
D.1238-65T 190 ° C / 5 kg 1.49 g / 10 min

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Claims (1)

Toil Pat e η t a η g r> r ü c Ii e Process for aiiionisclien polymerization of;: iiiidesteiis one of the vinylaromatic monomers styrene "and / or hydrocarbon-substituted styrenes with polymerization of the honor in .presence of a metal of the orctoii main group of the periodoric or of a hydrogen oil or a hydrocarbon compound thereof, since · by ■ ?, ek hen ₅ characterized in that as Ausgan ^ srnatcrial for Polynesia-.erisation- the starinonde from a Deliydrierurirjsres.lraion, nindestens 5 Sew.% of the / key again acknowl- "iGron cnrLaltende Eoiilenwasserstoffabstrom ^T employed. ri.rd- , ■ χ: -d dr.i? · R.indectens a 'part of the Polynerisationswlime in Hori.litioncf-Isr.isch. under stiffness run :; ¹ : the temperature for v / er.i - ": c" L "-iiir one. Ueil the duration of the action to over 100 '''C π ur üo 1:'. ■ -]! - ';!" j oil v / ird. V -.; - ri '? J.i_? E2 ^ after .Anbruch 1, thereby ^ ekennz eich- :: ot, uaü; 50 / j odor riehr der Polyiierisierungswärne in de :: Iieal: tionc ^c ce: .. iGCii surücli ^ ehalten v / erden. Get lost after imspruch Ί or 2, thereby ;; e 1: e η η - ζ cich η ο t that at least CO 70 of the Poi'ji.ierisations- \ i \ xriie in de:.: iw ^ Iraionsoenisch withheld;: ercen. Tcrfalircr after a:., The previous ;;; ehöenden -Ui ^ prüche, thereby e k e r · η ζ ei ■? h η ο t that the Γίυαίΐϊΐοη under practically adi abatic on condition; unp .: en dtiron.-cfür.rt uirdo 5- A method according to einor: aar previously _v; ehenau "claims, ^{dc.üurcli:.::} Eke η η ζ η et verifiable that the onperatur of He.xktionsgenisches for at least half of the V _a. '!'.. ktiono · v permanently held above 100 ⁰ G. ^r ird. BAD AUSTRIA 08828/0921 216117 6. Procedure according to one of the previous; ; eh 3nO "^ n claims, thereby characterized in that lithium metal as a catalyst or a lithium alkyl, aryl or aralkyl before x / ends will. 7 · Method according to claim 6, characterized in that : _; elrennseic Ii ■ -11 e "G that lithium buty is used as a catalyst. S. Verfallron according to claim 6 or 7> characterized in that the amount of active Eataiycators is 5 to ' ^Ί 5 πΗοΐ / l of vinyl aromatic ¹¹ conomers. 9 · Vc-rf ahren according to one of the preceding claims, characterized in that ς; ε indicates that styrene is practically in i'orra äoc .f. - :; a bo ε t ro no ε of dehydration; of ethylbenzene ρ ο Iyrericiart becomes. -; 0. Method according to one of the preceding claims, characterized in that ro denotes> that a discharge stron aor Dehyarian uncsreaction is used, which 30 G-ew.yi until SO G-ew. ^ a an Hcnomersm / Honoraeron contains » '■';. Process ei: according to one of the preceding claims.e, dadurcri ■ ~ 0 k D 11 11 3 0 ic -ine Ό ,;. ^; .-. .: j the i'ol ^ .Grl ^ r * oi '... ;; .. ^: .; 0 .-> tioncdav-or less than \ , jji ':. j. ^ boor:.'., -; ~ .- ^ 2. The method according to any one of the preceding claims, cx.c-urch [Jeke η η 2 verifiable et η, α ⁱ ate the Polyi.:3x iüatio2ioreaktionszeit JO nin or less betz'ägt. .'- ^. Method according to one of the preceding claims, characterized in that the polymerization is carried under appropriate selection as long as the Heaktionsbediiigungeii ^- is ilirt 'that the polymer satprodiüit an inherent viscosity of at least 0.5 has!. _ 14 - BATH ORIGINAL 2Ö3828 / 0S21 14. The method according to .Anspruch 1j5, characterized in that; that the intrinsic viscosity is 0.65 until 'i, 4. 15 · The method of any of the preceding claims, characterized in that the temperature of the reaction mixture Uird set at the initiation of polymerization in the range of 40 ⁰ C to 90 ⁰ C. 16. The method according to any one of the preceding claims, characterized in that the temperature rise in the reac
is carried out. turan increased in the reaction mixture up to x ^ enigstens 100 ⁰ C. 17 · Method according to one of the preceding claims, characterized in that the conversion of the monomer (s) to polymerize up to at least 80% is carried out. - 15 - 209828/0921 18. The method according to any one of the preceding claims, characterized in that the Active catalyst concentration and temperature of the reaction mixture at initiation within the area ABC of the following diagram? c Oll- OO3- A. \ \ \ _ \ \ f ^ B C) D. \ § ΟΌ- ΟΟ2 •
(D Ο · ΟΙ · \ \ 2Ο 4Ο 6Ο OO ΙΟΟ Ι2Ο ο
O
■ ^ ΟΟ8- \ φ
H
Eri O Initiation temperature 1 Ο-Ο6- • ( ⁰ C) 3 005 ο • Η ΟΟ4- i C. - 16 209828/0921 2151178 19. The method according to any one of the preceding claims, characterized in that the concentration of active catalyst and the temperature of the reaction mixture at initiation within the area DEFGH of the following diagram are: O , - ,,
U
a A. K D. \ \ F. ο ^OiC> \ \ •
1009- \ ¹ G \ O
O
• ^ 008 · \ \ B ω egg U
ο H 2Ο 4Ο 6Ο SO IQO I2O ω 0-06- Initiation temperature ο · '( ⁰ G) • rl OO4- OO3- OO2- C. σοι- - 17 - 209828/0921 20. The method according to one of the preceding claims. characterized in that the process is carried out continuously. 21. The method according to claim 20, characterized in that it is in one or more,
thermally insulated tube reactor / s is carried out. - 18 - 209828/0921 Blank page